NSData的使用

Objective-c

#if 0
//NSData的使用   也就是对把对象和基本数据类型的内容转换成二进制数据流
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //桌面路径
        NSString * path = [NSHomeDirectory() stringByAppendingString:@"Desktop/f1.txt"];
        NSString * temp = @"Hello Friend";
        NSArray * array = @[@"hello",@"world",@1];
        int i = 100;
        float f = 98.3333f;
        NSMutableData * writer = [[NSMutableData alloc] init];
        //给data 添加内容
        //1.添加data类元素
        /* - (NSData *)dataUsingEncoding:(NSStringEncoding)encoding;
         此方法只能由NSString 对象来调用
         */
        [writer appendData:[temp dataUsingEncoding:NSUTF8StringEncoding]];
        /*
         - (void)appendBytes:(const void *)bytes length:(   NSUInteger)length;
         这个方法用来给data 添加基本数据类型
         */
        [writer appendBytes:&i length:sizeof(i)];
        [writer appendBytes:&f length:sizeof(f)];
        //将数据写入到路径文件中
        [writer writeToFile:path atomically:YES];
        //下面来读取data数据
        int ii;
        float ff;
        NSString * ttemp;
        //读取文件中得数据
        NSData *reader = [NSData dataWithContentsOfFile:path];
        //
        ttemp = [[NSString alloc]initWithData:[reader subdataWithRange:NSMakeRange(0, [temp length])] encoding:NSUTF8StringEncoding];
        [reader getBytes:&ii range:NSMakeRange([temp length], sizeof(ii))];
        [reader getBytes:&ff range:NSMakeRange([temp length] + sizeof(ii), sizeof(ff))];
        NSLog(@"String:%@ int:%i float:%f", ttemp, ii, ff);
    }
    return 0;
}
#endif